Mul iband Sie pinski F ac al Pa ch An enna
C.
Bo~ja*,
J.
Romeu:
Elec omagne ics
&
Pho onics Enginee ing G oup, Dep . o
Signal Theo y and Communica ions, Uni e si a Poli knica de Ca alunya (UPC), c/
G an Capi a
sln,
Modul
D3
Campus No d UPC,
08034
Ba celona, Spain;
e-mail:
[email p o ec ed]; h p://www- sc.upc.es.
Abs ac
The mul iband beha io o he Sie pinski pa ch an enna is desc ibed in his
pape , and a new echnique o imp o e he mul iband beha io om he pin
o
iew o
he adia ion pa e ns is in cduced in
his
pape .
In oduc ion
The
use
o ac al geome ies is a new solu ion o design mul iband
an ennas. The mul iband beha io o he
Sie pinski
monopole has been p esen ed and
discussed, such monopole displayed a simila beha io o e i e bands om bo h
he
inpu e u n
loss
and he adia ion pa e ns pin o iew [l-21. The Sie pinski pa ch
an enna has been analyzed using an
I e a i e Neh o k
Model
[3]
and he inpu
impedance p esen ed a log-pe iodic dis ibu ion o
he
esonan equencies wi h a log-
pe iod ha is simila o he scale ac o be ween he iangles. The nex logical s ep is o
explo e he mul iband beha io o
he
Sie pinski pa ch an enna om he poin o iew
o
he adia ion pa e ns.
The adi ional Sie pinski pa ch an enna
The
geome y o he adi ional
Sie pinski pa ch an enna is displayed
in
Fig.l.a, he gaske is cons uc ed h ough ou
i e a ions,
so
ou -scaled e sions o he Sie pinski Gaske a e ound
on
he an enna
(ci cle egions in Fig.l.a), whe e he smalles is a single iangle. The e is a ac o
o
wo be ween scales, which
means
ha
he
Sie pinski Gaske heigh s
a e
88.9,44.5, 22.3
and 11.1
mm.
This pa icula shape has been chosen due o i s simila i y o he iangula pa ch
an enna [4]. The iangula like shape appea s a ou di e en scales, hen one could
expec ha a pa ch an enna wi h
his
ac al geome y would beha e simila ly o a
iangula pa ch an enna bu a ou di e en bands.
F om he poin o iew o he inpu impedance, he adi ional pa ch an enna p esen s a
mul iband beha io . The inpu esis ance and eac ance o he adi ional Sie pinski
pa ch displayed
in
Fig.1.a is plo ed in Fig.2. The pa ch is nume ically analyzed using a
MOM
code,
he
g ound plane is conside ed Mi e and
he
pa ch is
eed
by a coaxial
p obe. The inpu impedance p esen s ou esonan equencies (1.17, 2.57, 5.42 and
11.17
GHz)
co esponding o he ou subgaske s ha compose he Sie pinski pa ch, he
ou bands a e log-pe iodically spaced by a ac o o 6.2, which is exac ly
he
cha ac e is ic scale ac o ha ela es
he
se e al gaske sizes
wi hin
he ac al
shape.
0-7803-6369-8/00/$10.00
02000
IEEE
1708
__---_
3,'
sie pbk
"x
Pe u bed
Sie pinski
'>
'
Ai
:
.....
...
coaxialp obe
.il -------
Ai
:
.g
acoaxipbe
Tcod
pbe
(b)
Fig.1.
Geome y and con igu a ion
o
he
adi ional and
o
he
pe u bed
Sie pinski pa ch
an ennas.
The
sepa a ion be ween
he
g ound plane and
he
pa ch su ace is
h,=3
nun.
500
0
I2
3
4
5
6
7
8
9
1011
-500
ww
Fig.2.
Inpu esis ance and eac ance
o
he
adi ional Sie pinski and
o
he
pe u bed
Sie pinski pa ch an ennas.
The
p oblem is ha om he second band o he o h one, he high
o de
modes deg ade
he adia ion pa e ns, which ha e a null a
he
b oadside di ec ion.
The
deg ada ion
o
he adia ion pa e n is due o he ac ha
he
high o de modes
o
he Sie pinski pa ch
ha e a esonan equency simila o he esonan equencies associa ed o he
h ee
smalles subgaske s wi h heigh s
44.5,
22.3
and
11.1
nun.
The
cu en densi y
dis ibu ions o he ou esonan equencies a e displayed in Fig.3. I is in e es ing o
no ice ha a each band he cu en concen a es o e a p ope ly scaled subs uc u e on
he pa ch (ci cula egions in Fig.l), his egion becomes smalle when he equency is
inc eased. Howe e , o he second, hi d and ou h equency bands ela ed o he
Sie pinski iangles wi h heigh s
44.5,
22.3
and
11.1
mm
espec i ely,
he
high
o &
modes
associa ed o he Sie pinski gaske s o uppe i e a ions can be obse ed in he
cu en densi y dis ibu ions.
The
high
o de
modes
a e esponsible ha he cu en
densi y is dis ibu ed o e a egion ha
is
bigge han
he
egion co esponding a each
1709
subgaske . Fo ins ance, a
he
second band he cu en is high a he op junc ions
(do ed
line) while he subgaske associa ed a
his
band is only
44.5
mm
all.
Fig.3.
Cu en densi y dis ibu ions
o
he
adi ional Sie pinski pa ch.
The pe u bed Sie pinski pa ch an enna
In o de o educe he p esence o he
high o de modes a he second band, he geome y o he Sie pinski pa ch an enna is
modi ied
like
in Fig.1.b. The op junc ions
a e
b oken because he densi y cu en a he
second
band is ay high a hese
poin s
(Fig.3). and
his
b eaking o ce a minimum
densi y cu en in hese posi ions.
To
analyze he in luence o he b eaking in he inpu and adia ion pa ame e s he
pe u bed pa ch is analyzed using a
MOM
code. The con igu a ion and heigh
o
he
pa ch is displayed in Fig.
1
.b, and is simila o he adi ional Sie pinski pa ch.
The
inpu esis ance and eac ance a e plo ed in Fig.2. The main di e ences a e ha
a
new band appea s a 1.84 GHz
( his
esonan equency is
1.91
imes
bigge
han
he
ns one) and he ns esonance equency (0.96 GHz) is
1.2
imes
smalle han he
equency
o
he adi ional Sie pinski pa ch
(1.17
GHz).
The new band could be ela ed
o he esonan o he Sie pinski Gaske whose heigh is
44.5
mm,
since he scale ac o
be ween
he
wo equencies
is
e y close o 2, ha is he scale ac o be ween he
heigh s
o
he wo esonan iangles. The esonan equency a 2.62 GHz mus be
connec ed o he high o de mode o he alles Sie pinski iangle.
To
p ope ly dis inguish he
eal
in luence
o
he b oken junc ions on he pa ch adia ion
pa ans, he
main
cu s
($=O"
and
$=9O")
a e plo ed
in
Fig.4 o
he
h ee esonan
equencies whose alues e e 0.96, 1.84 and 2.62 GHz. The plo s ep esen he o al
pa e n wi h a 30
dB
dynamic ange. The pa e ns o he ns and second esonan
equency a e simila be ween hem and bo h a e b oadside. I is in e es ing o no ice
ha
he
pa e n a
2.6
GHz
has
a null a b oadside due o he p esence
o
he
high
o de
mode o he 88.9
mm
all Sie pinski Gaske .
1710
Fig.4.
To al
adimn pa e n
o
he
main
cu s
(+ P
and
$=90")
o
he
pe u bed
Sie pinki
pa ch an enna.
The
b eaking o he op junc ions lends o a pa ch an enna ha p esen s a b oadside
pa e n a wo bands, since
he
in luence
o
he
high
o de
modes a
he
second band a e
supp essed. F om he poin o iew o
he
adia ion pa e ns, he mul iband beha io
o
he Sie pinski pa ch an enna can be imp o ed b eaking he app op ia e junc ions.
Conclusions
A new echnique o imp o e he mul iband beha io om he poin
o
iew
o
adia ion pa e ns o he Sie pinski pa ch
has
been in oduced. The echnique
supp esses he e ec s o he
high
o de
modes and a pa ch an enna wi h simila adia ion
pa e ns can be designed. Once he
high
o de
mode has been supp essed o he second
band, he nex s ep
is
o
y
elimina e i
o
he hi d and o h band b eaking he
app op ia e junc ions.
Acknowledgmen s
Pa
o
his
esea ch has been inanced by he Eu opean
Commission
h ough
g an FEDER 2FD97-0135.
Re e ences
[l]
C.
Puen e, J. Romeu, R. Ba olome, and R.
Pous.
"Pe u ba ion o he Sie pinski
An enna o Alloca e Ope a ing Bands",
IEE Elec onics Le e s,
ol. 32, no. 24, pp.
2186-2187, No embe 1996.
[2] C. Puen e,
J.
Row,
R. Pous,
A.
Ca dama. "On he Beha io
o
he Sie pinski
Mul iband An enna",
IEEE T ansac ions on An ennas and P opaga ion,
ol. 46, no.
4, pp.517--524, Ap il 1998.
[3] C. Bo ja,
C.
Puen e, A. Medina. "I e a i e ne wo k model o p edic he beha iou
o a Sie pinski ac al ne wo k",
ZEEE
Elec onic Le e s,
ol. 34, no.
15,
pp. 1443--
1445,1998.
[4] Kai-Fong
Lee,
Kwai-Man-Luk, and Jashwan S.Dahele. "Cha ac e is ics o he
Equila e al T iangula Pa ch An enna",
IEEE T ansac ions
on
An ennas and
P opaga ion,
ol. 36, no. 11, pp.1510--1518, No embe 1988.
1711